Explore the vast range of titles available.

Diffusive losses of nitrogen and phosphorus from agricultural areas have detrimental effects on freshwater and marine ecosystems. Mitigation measures treating drainage water before it enters streams hold a high potential for reducing nitrogen and phosphorus losses from agricultural areas. To achieve a better understanding of the opportunities and challenges characterising current and new drainage mitigation measures in oceanic and continental climates, we reviewed the nitrate and total phosphorus removal efficiency of: (i) free water surface constructed wetlands, (ii) denitrifying bioreactors, (iii) controlled drainage, (iv) saturated buffer zones and (v) integrated buffer zones. Our data analysis showed that the load of nitrate was substantially reduced by all five drainage mitigation measures, while they mainly acted as sinks of total phosphorus, but occasionally, also as sources. The various factors influencing performance, such as design, runoff characteristics and hydrology, differed in the studies, resulting in large variation in the reported removal efficiencies.

Since the mid-20th century, Mediterranean lagoons have been affected by eutrophication, leading to significant changes in primary producers. In the early 2000s, management actions have been implemented to reduce nutrient inputs with the aim to achieve a good ecological status as requested by the EU water framework directive. As a result of these actions, a sharp decline in nutrient loads has been recorded in several lagoons leading to an oligotrophication of the water column. The analyses of a long-term data set (1998–2015) of 21 polyhaline and euhaline lagoons with contrasting trophic status allowed us to infer a general scheme for the changes in macrophyte assemblages during the oligotrophication process. Placing hypertrophic and oligotrophic conditions end to end, we inferred that the general pattern for the re-oligotrophication trajectory in Mediterranean coastal lagoons is described by the following sequence, with regime shifts between each state: (1) bare non-vegetated sediments, phytoplankton-dominated state; (2) opportunistic macroalgae; (3) seagrass and perennial macroalgae dominated state. However, we did not observe the latter regime shift for the most eutrophicated lagoons, which, so far, remained stuck in the opportunistic macroalgae state. So far, the shift from dominance of opportunistic macroalgae to a system dominated by seagrasses was only observed in a single lagoon where seagrasses had never completely disappeared, which possibly relates to resilience. More generally, the conditions favoring regime shifts from opportunistic macroalgae to seagrasses are still poorly understood. In conclusion, we describe a generic pattern for re-oligotrophication of Mediterranean coastal lagoons, although a full recovery from highly eutrophied to oligotrophic conditions may require more than a decade and may include conditions that remain so far poorly recognized.

Understanding the seasonal variation characteristics and trends in water quality is one of the most important aspects for protecting and conserving lakes. Lake Yangzong water quality parameters and nutrients, including water temperature, dissolved oxygen (DO), pH, conductivity, Chlorophyll-a, phycocyanin, total nitrogen (TN) and total phosphorus (TP), were monitored in different seasons from 2015 to 2021. Based on the monitoring data, the temporal and spatial variations of various parameters were analyzed. The results showed that Lake Yangzong is a warm monomictic lake. The Pearson correlation coefficient and correlation analysis showed water quality parameters were significantly correlated and probably affected by temperature. Cyanobacteria were at risk of blooming in spring and autumn. The contents of TN and TP in winter were significantly higher than in summer, especially TN, with both reaching a peak at the epilimnion and hypolimnion in December 2020 (TN = 1.3 mg/L, TP = 0.06 mg/L). We also observed a dual risk of endogenous release and exogenous input. Therefore, strengthening the supervision for controlling eutrophication caused by human activities and endogenous release is urgently needed.

To improve the quality of in vitro produced (IVP) embryos and reduce pregnancy losses, we proposed to reduce the components of the synthetic oviduct fluid (SOF) medium by 0% (SOF100), 50% (SOF50), and 75% (SOF25). First, embryos produced under these three treatments were evaluated for production, quality, lipid content, gene expression, and methylation patterns. The results indicated that all parameters analyzed were similar across all treatments ( P  > 0.05), suggesting that reducing media components does not affect embryo development and quality. Subsequently, we selected SOF25 for comparison with SOF100 in a commercial laboratory setting, evaluating embryo production, response to cryopreservation, gestation rate, and offspring birth. The data demonstrated that a 75% reduction in SOF medium components did not affect embryo development, quality, pregnancy rate, embryonic losses between 30 and 60 days, or birth rate ( P  > 0.05). To our knowledge, this is the first report on the pregnancy and birth rates of bovine blastocysts produced in media with nutrient concentrations as low as 25%. These results introduce novel cultural conditions that can be immediately incorporated into the IVF routine.

The Baltic Sea Action Plan (BSAP) requires tools to simulate effects and costs of various nutrient abatement strategies. Hierarchically connected databases and models of the entire catchment have been created to allow decision makers to view scenarios via the decision support system NEST. Increased intensity in agriculture in transient countries would result in increased nutrient loads to the Baltic Sea, particularly from Poland, the Baltic States, and Russia. Nutrient retentions are high, which means that the nutrient reduction goals of 135 000 tons N and 15 000 tons P, as formulated in the BSAP from 2007, correspond to a reduction in nutrient loadings to watersheds by 675 000 tons N and 158 000 tons P. A cost-minimization model was used to allocate nutrient reductions to measures and countries where the costs for reducing loads are low. The minimum annual cost to meet BSAP basin targets is estimated to 4.7 billion .

Interest in coastal restoration measures is increasing, but information about subsequent ecosystem recovery processes is limited. In Björnöfjärden on the Baltic Sea coast, Stockholm archipelago, a pioneering case study to reduce coastal eutrophication led to improvements and initially halved phosphorus levels. Here, we evaluate the effects of the restoration on the local fish assemblage over one decade after the measures. The study gives a unique possibility to evaluate responses of coastal fish to nutrient variables and abatement in a controlled natural setting. Cyprinid abundance decreased and perch partially increased with decreasing turbidity levels, while mean trophic level increased over time in the restored area. Responses were overall weak, likely attributed to an attenuation of the eutrophication abatement effect over time. The results suggest that nutrient reduction gives slow responses in fish compared to alternative measures such as fishing closures.

Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative propagules facilitating rapid initial growth and that can complete their life cycle by early summer. Later in the growing season these plants are, according to our simulations, outcompeted by periphyton, leading to late-summer phytoplankton blooms. Internal lake restoration measures often coincide with a rapid but transient colonization by hornworts, waterweeds or charophytes. Stable clear-water conditions and a diverse macrophyte flora only occurred decades after external nutrient load reduction or when measures were combined.

BackgroundA 4-year field study, on the adoption of a Biologically-Enhanced Agricultural Management (BEAM) protocol, in a cotton/cover-crop rotation in Turkey, was designed to observe “change-over-time” of soil organic carbon (SOC%) and total soil nitrogen (TSN%) at three soil profile depths (0–15 cm, 15–30 cm and 30–45 cm) while tracking farm productivity and profitability.MethodsBEAM systems employ regenerative practices: (a) no-till, (b) no, or reduced synthetic nutrient amendments, (c) continuous roots in the ground (commodity/cover), accompanied with an injection (in-furrow at planting) of an extract of beneficial microbes, from a Johnson-Su bioreactor. Three field nitrogen treatments: (1) BEAM+100% N (203 kg N ha−1); (2) BEAM+15% N (30.53 kg N ha−1); and (3) BEAM-0% N (No N applied), were implemented, on a 5.22-hectare plot, to assess the influence of BEAM protocols and nitrogen amendments, on SOC%, TSN%, cotton production, and profitability.ResultsThe SOC%, in the 0–15 cm soil profile demonstrated a significant increase from 0.39% SOC to 1.83% SOC, for a total increase of 1.44%, over the 4-year study period, (y = 0.3136x + 0.1206; r2 = 0.96; F(1,2) = 45.1616, p = 0.02143); The 15–30 cm soil profile demonstrated a non-significant loss of −0.23% SOC (y = −0.3161x + 0.156; r2 = 0.3183; F(1,2) = 0.9339, p = 0.4358), and the 30–45 cm soil profile exhibited a significant increase of 0.28% SOC; (y = 0.0477x + 0.4743; r2 = 0.9363; F(1,2) = 29.4005, p = 0.03237). Annual SOC cumulative increases of ~6.59 metric tons (t) carbon (C) ha−1yr−1, were observed, from 2019 to 2023, in the top 45 cm of the soil profile along with annual TSN increases of ~0.68 t N ha−1yr−1 in all three treatments. Cover-crop aboveground biomass increased annually in 2021, 2022 and 2023 from ~400 g, to ~692 g, to ~925 g dry biomass m−2yr−1 providing annual agroecosystem surface carbon accumulation of ~1.78 t C, ~3.08 t C and ~4.11 t C ha−1. Earthworm populations increased from zero earthworms m−2 in 2019 to ~100 earthworms m−2 in 2023. BEAM protocols also promoted: (a) farm input reductions of: 100% for herbicide, 56% for insecticide, 61% for diesel fuel, 85% for synthetic nitrogen fertilizer, and 100% for phosphorus fertilizer applications, reducing farm input costs ~$470 ha−1yr−1. Adoption of a BEAM regenerative agricultural management system, increased: (a) SOC (~6.59 t C ha−1yr−1); (b) C in the annual growth of cover-crop biomass (~4.12 t of C ha−1yr−1); (c) carbon in residual surface cover-crop plant residues from previous annual cover crops (~0.82 t C ha−1yr−1); and (d) C exported in cotton lint (~0.77 t C ha−1yr−1). Total C avoidance included: (a) reductions in fertilizer, pesticides and diesel inputs (~0.33 t C ha−1yr−1); and (b) reduction of C respiration from adoption of zero-till (~0.64 t C ha−1yr−1). Adoption of BEAM management, in this cotton/cover-crop agroecosystem, provided productive utilization, or avoidance of ~13.27 t of atmospheric C ha−1yr−1.

IntroductionTidal salt marshes provide critical ecosystem services in estuaries including the removal, storage, and transformation of nutrients, improving water quality and aquatic habitat. As tidal marshes drown from sea level rise, this service is lost, impacting estuarine resilience and leading to degradation of water quality. Living shorelines are a strategy to protect shorelines, while restoring some capacity to improve water quality. MethodsIn this study, we examine the magnitude of different nutrient storage and removal pathways in living shorelines, which range from short-term storage of nutrients (weeks-months) to permanent removals. ResultsWe found that all variables (plant and algal biomass, soil characteristics and sediment nutrient fluxes) varied significantly across sites emphasizing the variability in living shoreline functions. Plant biomass, benthic microalgae biomass, soil %C, soil %N, and denitrification (net N2 fluxes) were significantly different by season. Marsh age was only significantly correlated with phosphate fluxes from the sediment, so it was not an important driver of variability in function between living shorelines.DiscussionDespite the spatial variability, we found that nutrient storage and removal pathways were generally similar to those in natural marshes, reinforcing the assumption that these systems are replacements for natural marshes and an important component of resilience efforts. However, we found the short-term storage of nitrogen and phosphorus through uptake by benthic microalgae and the permanent removal of nitrogen through denitrification (both higher in living shorelines) suggests that living shorelines could maintain or improve estuarine water quality, contributing to coastal resilience.